Current Status of Electrical Metrology Standards Using Cryogenic Engineering Developments of Josephson Voltage Standards and Quantum Hall Resistance Standards, and their Applications

Abstract

This paper reviews the current status of electrical metrology standards using cryogenic engineering; i.e., Josephson voltage standards (JVSs) and quantum Hall resistance standards (QHRSs). The Josephson effect and the quantum Hall effect are widely used throughout the world for realizing the national standard systems for DC voltage and DC resistance, respectively. These effects provide intrinsic, essentially stable and accurate reference values based on the quantum theory. Recently, much effort has been made to expand the functions of the conventional systems to AC and other applications. In addition, in order to resolve the recent situation related to the worldwide liquid-Helium (LHe) shortage, we are promoting the development of LHefree JVS systems using closed-cycle mechanical coolers. These attempts are now reaching the practical stage and will have much importance for various fields.